Numbers

The Fourth Dimension

• First dimension: a line with no width
• Second dimension: a plane
• Third dimension: something with volume
• Fourth dimension: time

"It has been said that all modern aircraft have four dimensions: span, length, height—and politics.

"As Airbus engineers make the final preparations for the first test flight of its A400M military transporter next week, they will be hoping that the sight of the plane taking wing will help persuade European governments to commit to the program and shoulder some of its rapidly rising costs."—Nicola Clark, "Hopes for Costly Plane Are Riding on a Test Flight," The New York Times, December 4, 2009, p. B10.

How It's Used

"These two-dimensional pictures are fleshed out by looking at variations in the earth's gravitational and magnetic fields and its electrical conductivity at various depths. Another tool is seismic refraction, which measures the speed of sound waves from an underground explosion.

"The age of the rocks, which supplies the important fourth dimension to the map, is usually determined from isotopic analysis. This is possible because many rocks contain radioactive elements that decay into other elements on a precise schedule. Uranium, for example, will be half changed to lead after 4.5 billion years. This is on the order of the Earth's time scale, so geologists measure the relative amounts of the two elements in rocks to get a good idea of when the rocks formed."

"Dyer's preoccupations lead to Steinberg-like effects. He claims that his research is 'restricted to the forms of knowledge that are intrinsic to photographs, that can be intimated or extrapolated from them', but supplies detailed contexts for certain sequences—particularly the erotic activities of Alfred Steiglitz and Edward Weston, which heave up in the foreground—while leaving other sequences empty except for a few speculations in the distant vista. These are sometimes lovely, especially his monologue on the inner life of a park bench, or his understanding of the use of location to make time itself visible, receding down the side-alleys of the years.

"He gets near to saying that time is the fourth dimension of place that substitutes in photographs for the third, depth, which the camera can only map, not reproduce; the greatest images make the future, especially death, visible in the present moment—what you might call photomancy."

"That's no giant lying flayed on the floor at the University of Calgary in Alberta; it's a 4-D hologram generated by a new medical research tool called CAVEman. The tool lets researchers superimpose data such as CT scans, X-rays and biopsy results onto the floating image, projected into an empty space from three walls and the floor.

"Christoph Sensen, director of the university's Sun Center of Excellence for Visual Genomics, says it took his team six years to create the tool, which can help doctors and researchers study a disease's genetic composition and its effect on the body. Because CAVEman integrates many discrete pieces of knowledge in one space, it can help specialists see the big picture, Sensen says. Researchers can enlarge or shrink the hologram, focus on a single organ and even time-lapse the image (the fourth dimension) to see bodily functions and diseases progress."

"The energy shortfall could also limit the collider’s ability to test more exotic ideas, like the existence of extra dimensions beyond the three of space and one of time that characterize life."

Links